1. Field of the Invention
The present invention relates to a container for receiving articles such as, for example, a shopping cart for receiving goods, a sea freight container for transporting goods, a roll container which can be used in passenger aircraft for holding food and drink, a “rack” (e.g. IT server rack) for installing electrical and electronic devices etc.
In many areas of application it is desirable to be able to detect and identify articles actually accommodated in a container as simply and rapidly as possible.
2. Description of the Prior Art
RFID (“radio frequency identification” is a known technique for wireless identification of objects which has been used for some time in the area of so-called auto-ID, i.e. the automatic supply of information to persons, animals, goods, and articles.
Each auto-ID system is based on using artificial identification features to allow machine identification. The barcode labels still widely used today, which revolutionized the auto-ID area many years ago, are now becoming increasingly irrelevant to the cases of application which are gaining in importance today. One disadvantage of barcodes is frequently the low memory capacity for information, which also cannot be amended subsequently. In addition, the readout or readoff (“scanning”) of data is relatively inconvenient and time-consuming (visual contact is required).
These disadvantages can be eliminated with RFID. A large variety of RFID systems and methods are known per se. Merely as an example, reference may be made on this matter to the “RFID Handbook”, 3rd edition, Klaus Finkenzeller, Carl Hanser Verlag, Munich, Vienna 2002.
An RFID system consists of at least one reader for reading out data which are stored in a transponder, wherein the data transmission between transponder and reader takes place by means of electromagnetic waves. At lower frequencies, this takes place inductively via the near field, at higher frequencies via the electromagnetic far field. The reader, like the transponder, also can function as a transmitter and as a receiver for electromagnetic radiation. Inductively coupled systems possess a comparatively small range. Typical representatives of this variant are, for example, contactless chip cards and automatic access systems. On the other hand, systems with electromagnetic far-field coupling have a comparatively large range. Common frequencies of RFID systems with far field coupling lie in the order of magnitude of several hundred MHz. Frequently, quite specific frequency ranges are legally prescribed such as, for example, 865-869.5 MHz or 2.45 GHz.
In practice, many problems arise with the RFID systems and methods used at the present time, which make it difficult if not impossible to use RFID technology in many areas of application.
A first series of problems relates to the reliability of the technology. In this respect, there is a desire to identify all the transponders located in a detection zone of the respective reader and to read out data stored in these transponders free from error (and optionally to modify this free from error). In practice, however, this is prevented by, for example, interference of a plurality of RFID readers among one another, interference due to spontaneous radio emissions in the environment, interference due to other radio equipment and sometimes due to sabotage by interfering transmitters.
Another range of problems is data security. In this respect, for example, there is the risk of listening in to the data communication and the risk of spoofing information. Communication between an RFID reader and transponders is substantially comparable to a normal radio link between a transmitter and a receiver. An external eavesdropper can listen in on, falsify, simulate individual bit patterns or make the receiver unserviceable by overloading information in a manner similar to a denial-of-service (DoS) attack.
Known RFID systems have so far frequently failed because of the problems described above, particularly for identifying articles located in a container. Merely as an example, mention may be made of the hitherto previously unsuccessful experiments to detect the contents of shopping carts pushed past a checkout desk in a supermarket by means of an RFID system, that is, to identify separately and reliably the transponders integrated on or in the goods for each shopping cart. In this case of application, data transmission between transponder and reader is impaired, for example, by metal structures of the articles (e.g. tin cans) and also of the container (e.g. metal shopping carts).